A.G. Bain's land surveyor toolbox can be viewed at the Wellington museum

The year 1846 set the stage for the bulding of Bainskloof Pass. Bain was still busy with the construction of the pass at Mostertshoek when the colonial secretary, John Montagu and the surveyor general, Charles Bell departed from Mostertshoek on a journey via Worcester to visit the construction site at Houwhoek Pass. Shortly after their departure from Mostertshoek, Bain pointed to them a ravine which he spotted between the Limiet and Slanghoek mountains, directly in line with Wellington where he could build a pass through the mountain range between the Cape and the interior, connecting it to the pass at Mostertshoek.

Montagu immediately gave his permission for the project and Bain undertook a scouting expedition shortly thereafter. This turned out to be a rather difficult task as he had to persuade some of the local Wellington farmers to mobilise and accompany him on the arduous trip. The group consisted of a certain Retief, Septimus du Toit and two Malan brothers. Bain, who was already in his 50's, would later proclaim that day's reconnaissance journey the most difficult work day of his life. He was nevertheless satisfied with his discoveries and could report to the Central Road Board the feasibility of building a pass through the ravine. He was however also of the opinion that it would be no simple task.

A subsequent voyage through the ravine was undertaken later in the year together with the civil engineer, Bell, as well as reverend Dacres and a certain Josuas Rivers. The possibility of a pass was re-evaluated – this time from the side of the Breë River. The results were once again positive and Bell strongly commended the plan at the Central Roads Board, of which Montagu was the chairman. Montagu's official reaction was that Bain had to complete the Mostertshoek project with haste after which he would begin with the construction of Bainskloof Pass.

Bain's initial assignment was to build a service road through the ravine which could then be used to transport the labourers and equipment. The work started on 16 February 1849 with the help of a small group of convicts. By the end of March the remainder of the convict labourers who built Mostertshoek were transferred to Bainskloof. The several annual reports that were compiled by Bain for the Central Roads Board indicated that the labour force used for the construction were moved on a regular basis depending on certain variables, such as where their help was required as determined by the seasonal changes.

During 1849 they were mainly focused on the easier western side of the pass on Wellington's side of the mountain. Two stone bridges with wooden decks were built over larger streams while four stone passages were constructed over smaller streams, in addition to many chasms and trenches which received infilling. When in April of 1850 when Bain delivered his 1849 report to the Central Roads Board, the road was already passable up to the Neck at the highest point of the pass. He also mentions in the report that he planted a number of oak trees on the western edge of the road for shade.

Bain also had the idea of building a tunnel. While he planned two tunnels, only one were eventually constructed through a hill on the Wellington side of the mountain. The tunnel would have been 112 meter in length, 3.7 meter in width and 4.3 meter high. The tunnel, going through a slate hill, would have been the first of its kind in the Colony. Although completed in 1849, the tunnel would eventually collapse and Bain had to build his road around the hill.

The other tunnel he proposed, although rejected by the Roads Board, would have been positioned at the Neck so as to avoid the highest summit and thus reduce the road's length significantly. He planned to dig right through the mountain to reach the Wit River. Bain claimed that one advantage of such a tunnel would be that the farmers and residents of Wellington could be co-opted to assist with the expenses of the project because it will be possible to channel water from the Wit River through the tunnel for irrigation purposes in the valley just below the mountain.

After the largest portion of the pass were completed on the western side of the pass toward the end of 1849, buildings was erected for the approximately 60 convicts and the officers in charge of watching them, as well as a blacksmith workshop at the Pilkington River on the east side of the pass. This team was summoned for working on the service road toward Wolwekloof, better known today as Tweede Tol. The convicts who where at the station on the west side of the tunnel were moved to Wolwekloof from where about 60 of them started working on the service road to the Breë River.

The winter of 1850 caught Bain's building teams by surprise as planning for such heavy rains were not made. Not only did the rain delay the work with three months, but it also did extensive damage to the already completed parts of the pass through flooding.

The road was already completed up to the Neck when Bain compiled his 1850 report shortly before mid 1851. A stone building for the chaplain, a stable and feed barn and a smith shop was already built on the Neck. Bain suggested that these be sold in due time to establish a halfway station between Worcester and Paarl.

Another 295 oak trees were planted on the west side of the pass. 88 Poplar trees were also planted on the Neck, but Bain doubted whether they would be able to withstand the great southeaster wind that blew there.

Construction on the service road from the Neck towards the Breë River started on the 1st of January 1850. This part would however present many problems and Bain describes how the quartzitic sandstone rocks and the various ravines caused significant reduction in the pace of his work teams on the east side of the mountain.

The work were done in segments from the Neck to Wolwekloof. This part of the pass had to go along the precipitous slope above the Witte River. Huge amounts of rock had to be chopped away in order to provide buttresses against the slopes with broken rock as well as the gaps where the road had to go over a fissure. In his own words he reported as follows: “The nature of the work here is quite different from the other side of the mountain, the line passing through high masses of fixed and detached quartzose rock, which seems set at defiance the engineer’s skill to construct anything like a well graduated road through it: for no sooner is one obstacle removed, in the shape of an enormous block of rock of scores of tons of weight, then others appear in rapid succession, such as rugged transverse krantzes, etc., of which there seems to be no end; but the powerful agency of gunpowder is making them slowly disappear…”. The fact that £1223 were spent on gunpowder is a good indication of the amount of times they had to make use of it – there were no such thing as dynamite in those days.

The buttresses were built using the drystone method since cement was not invented yet. The rocks were chiseled and fitted so that it would press against each other in a symmetric fashion, thereby supporting the overhead road itself. A characteristic advantage of these types of structures was that the more weight applied on top, the stronger the supporting walls would become.

By the middle of 1850 there were already several loose parts on the east side that were passable by wagons. Bain could then report that there were about 300 meter of the easier and more level part from the Neck completed and that it only required a gravel coating. Also completed was a stone bridge and buttresses for about 200 meter's wagon road, situated a few hundred meters from the main station on the Neck.

At Montagu Rocks he had to break a path through a rock mass that were about 5 meter wide, 7 meter tall and 60 meter in length. A miniature railway had to be used at this stage to carry the broken rocks to the river openings to provide infilling and buttresses to complete about 200 meter of wagon road.

The most difficult part of the road was the section running from Montagu Rocks and stopping just short of Wolwekloof. Gunpowder was used at various locations to get past the huge rock formations and create a port for the pass. This was also the location where buttresses of up to 19 meter high had to be constructed to support the road against the steep cliffs.

In his 1851 report Bain writes that large parts of the road between the Neck and the Pilkington River was already completed, but hat the precipitous cliffs of up to a 100 meters were causing significant delays. The Pilkington Bridge, which had to be built 18 meters high, struggled to reach the point of completion and was a hindrance to the traffic trying to reach other parts of the completed pass.

Another part of the road which who’s construction got hampered during 1851 were the piece between Wolwekloof and the Steenboks River which lied hill-down, closer to the Breë River's side. However the flat part from the Steenboks River to the Breë River did have a drivable surface which were used for the transport of supplies to Wolwekloof.

Already in 1851 did Bain start to complete the approach roads leading to the pass. For this he added three more outposts. The first was at the Breë River for a team of convicts who had to assist with the building of a bridge with which to cross the river. The second outpost, which was also erected for the purposes of building a bridge as well as to help with the road construction between Michells Pass and Bainskloof, was positioned nearby Michells Pass. The third outpost was placed close to Wellington to work on the approach road between the pass and the town as well as a bridge that would cross the Breë River.

By the 5th of November 1852 the Darling Bridge over the Breë River was completed by W.H. Manning, who shortly thereafter, were to build a bridge crossing the Breë River between Paarl and Wellington. Furtherore, thanks to intensive convict labor the wagon road of 14.5 kilometer between the Darling bridge and Michells Pass could also be opened for road users.

By April of 1853 all the unfinished parts of the road were connected. The pass were lined with 16 kilometers of almost uninterrupted prop wall. The road work between the pass and Wellington and from the town to the Berg River – as well as its bridge – were also nearing completion. A group of convict laborers were still busy applying several finishing touches when the pass officially opened on 14 September 1853. The total construction cost of the pass amounted to £50,999.

The pass's official opening was held during a prestigious ceremony which attracted dignitaries from afar. They departed from Cape Town on Monday 12th September 1853 and received a regaled reception in Wellington where they remained for the night. The following morning the new bridge crossing the Berg River just outside of Wellington was also opened in ceremonial fashion. A triumphal arch made of heather flowers was spanning Bain Street with rows of flags positioned on the sides. In the evening a banquet was held for the guests of honor.

The entire retinue shifted towards Bainskloof on Wednesday morning, the 14th of September. A toast were drank on the Neck before they proceeded with the march. Triumphal arches were placed over the Montagu and Bell rocks and spanning the Pilkington and Borcherds bridges. At Wolwekloof the guests were surprised with the firing of 21 shots shot from three different mountain peaks and a rock which were blown in the air with gunpowder. P.B. Borcherds, chairman of the Central Roads Board, gave the opening speech of the pass. The bridge over Wolwekloof's stream were subsequently named after him. Several speeches followed accompanied by more toasts.

After one o'clock that afternoon the procession moved to the Darling bridge crossing the Breë River where it was also officially inaugurated and paired with a sumptuous meal. From there the dignitaries went to Worcester for the night. On Thursday morning they returned to Bainskloof, along the way stopping at Wolwekloof to drink a toast on Andrew's son, Thomas Bain, the superintendent of the Wolwekloof station, where after they proceeded over the pass back to Cape Town.

Bainskloof pass was thus properly launched and would until 1949, when Du Toitskloof Pass were opened, operate as the main route to the north.